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January 21, 2017
Posted by **Habooba** on Thursday, December 8, 2011 at 8:13am.

- math -
**Reiny**, Thursday, December 8, 2011 at 9:17am4th term is 3 times 1st term ----> a+3d = 3a

2a = 3d

a = 3d/2

7th term exceeds the 3rd term by 1

a+6d > a+2d by 1

a+6d = a+2d + 1

4d = 1

d = 1/4

then a= (3/2)(1/4) = 3/8

**10th term = a+9d = 3/8 + 9(1/4) = 21/8**

check: a=3/8, d=1/4 or 2/8

3/8, 5/8, 7/8, 9/8, 1/8, 13/8, 15/8, 17/8,19/8,21/8 ....

is 10th term 21/8 ? , yes

is 4th term 3 times the fist ? is 9/8 three times 3/8 ? yes

is 7th term bigger than 3rd term by 1 ?

is 15/8 - 7/8 = 1 ? yes

all is good